Modem and facsimile apparatus capable of monitoring G3 communications via ISDN

ABSTRACT

A facsimile use modem apparatus includes an analog interface formed from a silicon data access arrangement interfacing with an analog telephone line. A digital interface is provided to interface with an ISDN line. A signal converting device is provided to convert a modem signal used in facsimile communications via the analog telephone line into a signal used in the ISDN line, vice a versa. A data transmitting device is provided to transmit linear data to a monitor via the silicon data access arrangement when G3 facsimile communications are performed via the ISDN line so as to monitor a progress of the G3 facsimile communications.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent file or records, but otherwise reserves all copyrightrights whatsoever.

BACKGROUND

1. Field

The present specification relates generally to modems and facsimileapparatuses which execute G3 and G4 facsimile communications throughtelephone and ISDN lines, and in particular to such modems and facsimileapparatuses which employ a silicon DAA (Data Access Arrangement) circuitcapable of monitoring G3 communications executed via the ISDN.

2. Discussion of Related Art

A conventional electric circuit forming a central core of a facsimileapparatus can generally be categorized into an FCU (facsimile controlunit) and an NCU (network control unit) as shown in FIG. 3.

The FCU 101 includes a controller section 102 which controls variousinstruments built in a facsimile and a modem section which appliesmodulation/demodulation to a facsimile signal. The modem sectiontypically includes a modem DSP (Digital Signal Processor) 103 performingdigital signal processing. Also included in the modem section is an AFE(Analog Front End) section 104 having a CODEC(Compression/Decompression) which performs AD/DA conversions and anoperational amplifier which adjusts a facsimile signal to a specifiedlevel.

The NCU 105 interfaces with a telephone line and is formed from aninsulation transformer 106 which insulates the telephone line 109(hereinafter referred to as a primary side) from the FCU 101(hereinafter referred to as a secondary side), a direct current circuit107 which meets a direct current closure standard for the telephoneline, and a ring detection circuit 108 which detects a ring signal ofthe telephone line and so on.

As a facsimile communications system, widely spreading G (Group) 3communications and high-speed G4 digital communications operating via anISDN line are exemplified. According to the G3 communications system, atransmission modem temporarily converts a digital signal into an analogsignal and then transmits the analog signal through a telephone line,and a reception modem converts the analog signal into digital data. Incontrast, the G4 communications system transmits a digital signal as isvia the ISDN line.

Such communications are performed without any problem betweencommunication systems of the same type. However, due to a difference ina type of a communications system, a G3 facsimile apparatus and G4 afacsimile apparatus cannot communicate with each other unless one orboth of them are adapted for such communication. For example, afacsimile apparatus having a function of G4 communications can include aG3 communications function in order to communicate with a facsimileapparatus operating in the G3 system. In such a situation, however,although a user installs and connects the IDSN line to his or her G4facsimile apparatus, a communications counterpart is limited to a G3facsimile apparatus when the G4 facsimile apparatus performscommunications in a G3 mode via the ISDN line as shown in FIG. 4.

Specifically, facsimile signals input and output to and from the modemDSP 205 undergo AD/DA conversion in the CODEC0 section 206. Whencommunications are performed via a conventional PSTN (Public SwitchedTelephone Network), input and output terminals of the CODEC0 section 206are connected to the NCU and the PSTN line via an insulationtransformer. Input and output signals to and from the CODEC0 section 206are mixed in the addition amplifier 209 and are output from a speaker207 as a mixture signal generating a sound. Thus, a facsimile signal onthe PSTN line can be aurally monitored.

On the other hand, when facsimile communications are performed via theISDN line, an SW1 section 208 switches a connection destination of theinput and output terminals of the CODEC0 section 206 from the NCU to theCODEC1 section 202. The CODEC1 section 202 converts a facsimilecommunications signal transmitted from the CODEC0 section 206 into adigital signal of 8 bits having undergone μ/Alaw or μ/law conversioncommunicable at 8000 Hz sampling frequencies for the ISDN line. Suchdigital signal is then launched into the ISDN line via an ISDN interfacesection 203. Similar to the PSTN line connection, a facsimile signal onthe ISDN line can be aurally monitored from the speaker 207.

It is increasingly the case recently that in such an environment, datamodems employ a low cost and downsized silicon DAA (Data AccessArrangement) instead of using the above-mentioned transformer. With sucha configuration, a problem which likely occurs in such a facsimile isthat the G3 facsimile communications cannot successfully be performedvia the ISDN. A countermeasure against the problem has been developedsuch that digital data subjected to sampling rate conversion to 8000 Hzand μ/Alaw or μ/law conversion is used to communicate between the datamodem and the ISDN line.

Further, as an insulation device insulating the FCU from the telephone(PSTN) line, an NCU employing an insulation transformer isconventionally adopted. It is increasingly common, however, that datamodem apparatuses employ a silicon DAA having an insulation device suchas a condenser. Thus, it is more common now that a facsimile apparatuswill use a silicon DAA as shown in FIG. 5.

Specifically, the silicon DAA utilizes such an insulation condition of acondenser and is typically formed from a system side device 305 and aline side device 307 coupled through the insulation condenser 310. Insuch a facsimile apparatus, a facsimile communications signal from themodem DSP section 304 is converted into a signal capable of passingthrough the insulation condenser 310 from the system side device 305, tothe line side device 307. The line side device 307 converts the signalfrom the modem DSP 304 with a built-in CODEC section 3071 and outputs ananalog signal to a line. In contrast, an input signal received via thePSTN line undergoes A/D conversion in the built-in CODEC section 3071,and is transmitted to the system side device 305 via the insulationcondenser 310, which is ultimately input to the modem DSP 304.

However, when facsimile communications are performed via the ISDN linefrom the conventional system of FIG. 3 employing the silicon DAA, theISDN communications block of FIG. 4 must be connected to the system. Asa result, the input to and output from the ISDN communications block areenough to directly communicate with the CODEC1 section 202, andaccordingly, the system of the silicon DAA has no provision (i.e., datacommunication route) to transmit a facsimile communications signal to asystem side device 305 of the secondary side connecting to a speaker.

Further, due to an 8 bits and μ/Alaw or μ/law conversion receivingdigital signal communicable at 8000 Hz through the ISDN line, theabove-mentioned facsimile communications signal cannot be monitoredthrough the speaker if such a format is maintained. That is, theseinputs to and outputs from the modem DSP 304 and the system side device305 are entirely digital signal states, and there are no analog signalsfor driving the speaker.

SUMMARY

The present disclosure provides various examples and embodiments of anew modem and facsimile apparatus capable of monitoring G3 facsimilecommunications through an ISDN line.

In an aspect of this disclosure, a novel modem (and facsimile apparatus)is provided which includes an analog interface formed from a silicondata access arrangement operative to interface with an analog telephoneline, a digital interface operative to interface with the ISDN line, anda converting device which converts a modem signal communicated via theanalog telephone line into a signal communicated via the ISDN line, vicea versa.

In a preferred embodiment, a transmitting device transmits lineardigital signals to a speaker via the silicon data access arrangementwhen G3 facsimile communications are performed through the ISDN line inorder to aurally monitor a progress of the G3 facsimile communications.

In another exemplary embodiment, the speaker driving use signal isgenerated by combining facsimile sending and reception signals.

In yet another exemplary embodiment, a volume adjusting device isprovided to multiply each of the facsimile sending and reception signalsby a prescribed gain and adjust a volume of the speaker usingcalculation resulting data.

In yet another exemplary embodiment, a data canceling device is providedto cancel excessive facsimile communications data when a samplingfrequency of the facsimile reception signal from the ISDN line is higherthan that of the modem.

In yet another exemplary embodiment, a noise suppressing device isprovided to suppress noises likely generated by the speaker byrepeatedly using the same sampling data when the sampling frequency ofthe facsimile reception data is lower than that of the modem.

In yet another exemplary embodiment, the silicon data accessarrangement, speaker, and ISDN interface collectively forms a networkcontrol unit of the facsimile.

BRIEF DESCRIPTION OF DRAWINGS

A more complete appreciation of the present disclosure and many of theattendant advantages thereof can be more readily understood from thefollowing detailed description when considered in connection with theaccompanying drawings, wherein:

FIG. 1 illustrates an exemplary facsimile use modem apparatus inaccordance with a preferred embodiment of the present invention;

FIG. 2 illustrates an exemplary speaker circuit, according to apreferred embodiment of the present invention;

FIG. 3 illustrates a conventional electric circuit forming a centralcore of a facsimile apparatus;

FIG. 4 illustrates a conventional connection between an ISDN line and afacsimile apparatus provided with G3 and G4 functions;

FIG. 5 schematically illustrates FCU and NCN sections formed from asilicon DAA; and

FIGS. 6A and 6B illustrate linear data transmitted to the speaker of thepreferred embodiment of the present invention.

PREFERRED EMBODIMENT OF THE PRESENT INVENTION

A description of some exemplary embodiments is provided below withreference to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout several views.

In particular in FIG. 1, a modem DSP chip 405 (i.e., a modem DSPsection) is formed from, but is not limited to, a DSP section 406 whichapplies modulation and demodulation processes to a facsimile signalusing a digitizing process, a serial interface section 407 whichperforms serial data communications with a system side device 409 formedfrom, but is not limited to, a silicon DAA, and a serial interfacesection 408 performing serial data communications with an ISDN interfacesection 403.

When facsimile communications are performed with a PSTN line 412,communications data (for example, a facsimile signal) from the DSPsection 406 may be converted into a prescribed interface format by theserial interface section 407 to be used in the modem CODEC 4101. Such aninterface format may include a linear data of 16 bit length communicableat various sampling frequencies in accordance with a connection phaseand/or a symbol rate.

A system side device 409 can handle the interface format, and converts afacsimile signal (for example, communication data) transmitted from theDSP section 406 into a signal capable of passing through the insulationcondenser 415. The facsimile signal transmitted through the insulationcondenser 415 is launched into the PSTN line as an analog signal throughthe line side device 410. The system side device 409 preferably includesan analog output terminal connected to a speaker 414 and is designed tomonitor a communications condition on the PSTN line if equipped withsome amount of analog circuits.

When facsimile communications are performed with the ISDN line,communications data from the DSP section 406 having 16 bits linear datacommunicable at various sampling frequencies in accordance with aconnection phase and/or a symbol rate may be converted into an interfaceformat formed from an 8 bits μ/Alaw or μ/law data communicable at 8000Hz sampling frequencies by a serial interface section 408 to be used inthe ISDN interface.

Specifically, the sampling frequency of the communications data from theDSP section 406 may be converted into 8000 Hz from an original samplingfrequency such as 9600 Hz, 7200 Hz, etc., by a sampling conversionfunction 4061. The μ/Alaw or μ/law conversion function 4062 may convertthe 16 bit linear data into an 8 bit μ/Alaw or μ/law data format.

The data converted in such a manner is then transmitted to an ISDNinterface section 403 by the interface section 408 and is launched intothe ISDN line after being converted into a prescribed condition meetingthe ISDN standard.

In such a system, when G3 communications are performed via the ISDNline, since a signal expected to exit thereto in an analog state isstill the 8 bits and μ/Alaw or μ/law data format, a user cannot confirma communications condition on the ISDN line in accordance with a soundif such a format is maintained.

According to the preferred embodiment of the present invention, lineardata generated in the modem DSP 406 as shown in FIG. 6A is preferablygiven, as is, to the silicon DAA not operating during the G3communications, which is directly performed via the ISDN line detouringthe system side device 409. The linear data may then be transmitted tothe speaker via the analog output terminal of the silicon DAA.

Further, the transmission signal is the digital linear data notsubjected to the μ/Alaw or μ/law conversion in the modem DSP 406 asmentioned above, and a reception signal of μ/Alaw or μ/law data isconverted into linear data when demodulated by the modem DSP. Hence, ifsumming and transmitting the above-mentioned transmission and receptionlinear data to the speaker via the analog output terminal, a sound canbe generated (and heard) in both directions. Stated differently, evenduring G3 communications via the ISDN, a line signal representing acommunications condition can similarly be monitored by a user, when thefacsimile communications are performed via the conventional analog line,if a μ/Alaw or μ/law signal flowing though the ISDN line at 8000 Hz isconverted into PCM data to be transmitted to the speaker via the siliconDAA. Thus, such a silicon DAA and speaker circuit can form the NCU ofthe modem apparatus of the facsimile according to the preferredembodiment of the present invention.

An other embodiment of a speaker circuit is now described with referenceto FIG. 2. The speaker circuit occasionally needs sound volumeadjustment depending upon a type of its parts and circuit configuration.The speaker circuit preferably entails a system multiplying theabove-mentioned linear data by a gain on the DSP side before the productis sent to the silicon DAA. Specifically, each of the transmission andreception signals is preferably multiplied by the gain, and the productof such calculation is preferably sent to the system side device. If again is preset to the DSP section 406 by a controller, a system designercan set an optimum level to the speaker circuit.

Further, when a speaker monitors G3 communications executed via the ISDNin the above-mentioned manner, clock deviation likely occurs as aproblem. Specifically, when the G3 communications are performed via theISDN, a sampling frequency used in a silicon DAA is generally set to asuitable level for the modem to operate, such as 7200 Hz, 9600 Hz, etc.,as in its ordinary operation. Thus, since a sampling frequency used inthe ISDN is generally 8000 Hz, the sampling frequency of the ISDN isattempted to undergo the sampling conversion so as to synchronize withthat of the modem clock.

Some deviation, nevertheless, may remain there between. That is becausecommunication data flows through the ISDN line at a prescribed frequencyof 8000 Hz, and the silicon DAA generates sampling clocks by dividing amaster clock transmitted thereto. In short, these clocks can originatefrom different sources.

Further, a sampling clock having a fine frequency such as the 50 ppmlevel is usually employed for a silicon DAA. Deviation in a samplingfrequency between the silicon DAA and the ISDN may amount to about 100ppm, if any. For example, if the sampling frequency of the modem amountsto 9600 Hz, overs and shorts may be about 0.96 samples per second ascalculated by the following formula:9600×100/1000000=0.96In such a situation, dropout of only a sample from communications datato and from the modem may cause deviation of phase and samplingsynchronization, thereby resulting in a fatal data error duringcommunications. Such deviation, however, may be permissible to theextent a communications condition can be heard without uncomfortablefeeling when monitored by an operator via the speaker. Therefore, ifsuch a sample is short, the same sampling data is repeatedly used asillustrated in FIG. 6B.

In contrast, if such a sample is excessive, an excessive sample may beomitted. By controlling in such a manner, the communications conditioncan be monitored in any cases via the speaker substantially excluding aplosive sound.

The above specific embodiments are illustrative, and many variations canbe introduced on these embodiments without departing from the spirit ofthe disclosure or from the scope of the appended claims. For example,elements and/or features of different illustrative embodiments may becombined with each other and/or substituted for each other within thescope of this disclosure and appended claims.

This application claims priority under 35 U.S.C. §119 to Japanese PatentApplication No. 2003-015532, filed on Jan. 24, 2003, the entire contentsof which are incorporated by reference herein.

1. A facsimile use modem apparatus, comprising: an analog interfaceformed from a silicon data access arrangement operative to interfacewith an analog telephone line, said analog interface including aninsulation device configured to insulate a remainder of said facsimileuse modem apparatus from said analog telephone line; a digital interfaceoperative to interface with an ISDN (integrated services digitalnetwork) line and configured for G3 communications through the ISDNline; a signal converting device configured to convert a modem signalused in facsimile communications via the analog telephone line into afirst signal used in the ISDN line, and convert a second signal from theISDN line into a converted signal for use in facsimile communicationsvia the analog telephone line; a monitoring device located within thesilicon data access arrangement and configured for monitoring a progressof the facsimile communications via the ISDN line; and a datatransmitting device operative to transmit linear data to a speaker viathe silicon data access arrangement; a system side device connecting thesilicon data access arrangement and the digital interface that enablestransmission of signal through an insulation condenser to thereby enablesaid monitoring device located within the silicon data accessarrangement to monitor G3 communications executed through the ISDN line.2. The facsimile use modem apparatus according to claim 1, wherein saidlinear data is formed from facsimile sending data and facsimilereception data.
 3. The facsimile use modem apparatus according to claim2, further comprising a volume adjusting device configured to multiplyeach of the facsimile sending data and facsimile reception data by aprescribed gain when a volume of the speaker is adjusted.
 4. Thefacsimile use modem apparatus according to claim 1, further comprising adata canceling device configured to cancel excessive facsimilecommunications data when a clock of the ISDN line is faster than that ofthe modem.
 5. The facsimile use modem apparatus according to claim 4,further comprising a noise suppressing device operative to suppressnoises output from the speaker by repeatedly using a previous data whenthe clock of the ISDN line is slower than that of the modem.
 6. Thefacsimile use modem apparatus according to claim 2, wherein said silicondata access arrangement, speaker, and ISDN interface collectively form anetwork control unit of the facsimile.
 7. A facsimile apparatusincluding a facsimile use modem comprising: an analog interface formedfrom a silicon data access arrangement operative to interface with ananalog telephone line, said analog interface including an insulationdevice configured to insulate a remainder of said facsimile use modemapparatus from said analog telephone line; a digital interface operativeto interface with an ISDN (integrated services digital network) line andconfigured for G3 communications through the ISDN line; a signalconverting device configured to convert a modem signal used in facsimilecommunications via the analog telephone line into a first signal used inthe ISDN line, and convert a second signal from the ISDN line into aconverted signal for use in facsimile communications via the analogtelephone line; a monitoring device located within the silicon dataaccess arrangement and configured for monitoring a progress of thefacsimile communications via the ISDN line; and a data transmittingdevice operative to transmit linear data to a speaker via the silicondata access arrangement; a system side device connecting the silicondata access arrangement and the digital interface that enablestransmission of signal through an insulation condenser to thereby enablesaid monitoring device located within the silicon data accessarrangement to monitor G3 communications executed through the ISDN line.8. A network connecting a facsimile apparatus having a facsimile usemodem comprising: an analog interface formed from a silicon data accessarrangement operative to interface with an analog telephone line, saidanalog interface including an insulation device configured to insulate aremainder of said facsimile use modem apparatus from said analogtelephone line; a digital interface operative to interface with an ISDN(integrated services digital network) line and configured for G3communications through the ISDN line; a signal converting deviceconfigured to convert a modem signal used in facsimile communicationsvia the analog telephone line into a first signal used in the ISDN line,and convert a second signal from the ISDN line into a converted signalfor use in facsimile communications via the analog telephone line; amonitoring device located within the silicon data access arrangement andconfigured for monitoring a progress of the facsimile communications viathe ISDN line; and a data transmitting device operative to transmitlinear data to a speaker via the silicon data access arrangement; asystem side device connecting the silicon data access arrangement andthe digital interface that enables transmission of signal through aninsulation condenser to thereby enable said monitoring device locatedwithin the silicon data access arrangement to monitor G3 communicationsexecuted through the ISDN line.
 9. The facsimile use modem apparatusaccording to claim 1, wherein said signal converting device includes aDSP section, and said DSP section converts a facsimile transmissionsignal or facsimile reception signal to generate the linear datasupplied to the speaker.
 10. The network connecting the facsimileapparatus having the facsimile use modem according to claim 8, whereinsaid linear data is formed from facsimile sending data and facsimilereception data.
 11. The network connecting the facsimile apparatushaving the facsimile use modem according to claim 10, wherein thefacsimile use modem further comprises a volume adjusting deviceconfigured to multiply each of the facsimile sending data and facsimilereception data by a prescribed gain when a volume of the speaker isadjusted.
 12. The network connecting the facsimile apparatus having thefacsimile use modem according to claim 8, wherein the facsimile usemodem further comprises a data canceling device configured to cancelexcessive facsimile communications data when a clock of the ISDN line isfaster than that of the modem.
 13. The network connecting the facsimileapparatus having the facsimile use modem according to claim 12, whereinthe facsimile use modem further comprises a noise suppressing deviceoperative to suppress noises output from the speaker by repeatedly usinga previous data when the clock of the ISDN line is slower than that ofthe modem.
 14. The network connecting the facsimile apparatus having thefacsimile use modem according to claim 10, wherein said silicon dataaccess arrangement, speaker, and ISDN interface collectively form anetwork control unit of the facsimile.
 15. The facsimile apparatushaving the facsimile use modem according to claim 7, wherein said lineardata is formed from facsimile sending data and facsimile reception data.16. The facsimile apparatus having the facsimile use modem according toclaim 15, wherein the facsimile use modem further comprises a volumeadjusting device configured to multiply each of the facsimile sendingdata and facsimile reception data by a prescribed gain when a volume ofthe speaker is adjusted.
 17. The facsimile apparatus having thefacsimile use modem according to claim 7, wherein the facsimile usemodem further comprises a data canceling device configured to cancelexcessive facsimile communications data when a clock of the ISDN line isfaster than that of the modem.
 18. The network connecting the facsimileapparatus having the facsimile use modem according to claim 17, whereinthe facsimile use modem further comprises a noise suppressing deviceoperative to suppress noises output from the speaker by repeatedly usinga previous data when the clock of the ISDN line is slower than that ofthe modem.
 19. The network connecting the facsimile apparatus having thefacsimile use modem according to claim 15, wherein said silicon dataaccess arrangement, speaker, and ISDN interface collectively form anetwork control unit of the facsimile.